They follow Cyril's footprints. The other footprints are getting bigger, Lily notices. "Whatever your brother is following," the Doctor says, "is growing." Lily runs a few steps ahead, brushing against a tree as she does so. Snot ornaments drip from its branches. "Naturally occurring Christmas trees," the Doctor says. "How cool is that?" It'd be cooler without the mucus. The Doctor's glee fades as he hears the trees whispering. He says he's been there before but he's never seen the trees so active. "Something is wrong." He peers into one of the booger ornaments and sees a bark-covered face staring back at him. Back at Uncle Digby's house, Madge has just discovered the opened gift under the tree. Cyril's tracking has led him to something that looks like a lighthouse with a geodesic dome on top.
Madge wanders around Narnia looking for her children. At the same time, Cyril ventures into the lighthouse and finds a tree in the shape of a bearded man. Treebeard -- let's call him -- sits in a throne while dramatic music plays. The tracks lead directly to the throne. Instead of pooping himself and running screaming into the night, Cyril presses further on into the lighthouse. Treebeard blinks and turns his head with the creaking of wood.
The Doctor is explaining to Lily how this planet is one of the safest places he knows when, as if to prove him wrong, the ground shakes suddenly with an unknown impact. The ground shakes again and again. Elsewhere, Madge comes upon its source: a large, robotic vehicle with hydraulic legs. A light comes on at the top of it and a voice booms, "This tree farm is private property! You are trespassing!" A door opens in one of the legs and three people in hazard gear step out. They have weapons. "I think she's a time-traveler," a woman says, scanning her. Reaching the end of her rope, Madge sobs and cries.
Cyril makes his way into the dome portion of the lighthouse. The door closes behind him. Beyond there is a throne. A tree woman stands over it, a wooden grown atop her head and a thin gold circlet in her hands. Lily and the Doctor race into the lighthouse and find Treebeard. The Doctor sees the tracks and surmises this was what Cyril was following. The Doctor gets all flustered the way he does when he sees clever things, because the entire building is made of trees that have grown together just so. He also surmises that the whole thing with its very tempting doors is a "people trap," but why would a forest need people? Maybe to hear when a tree falls.